1. Field of the Invention
The present invention generally relates to an electric vehicle including an electric motor as a driving power source. Particularly, the present invention relates to regenerative braking control during deceleration of the electric vehicle.
2. Description of the Related Art
Conventionally, in an electric vehicle including an electric motor as a driving power source, during deceleration, the motor is actuated by a force applied by wheels. Thereby, the motor generates a braking force to be applied to the wheels, and operates as an electric generator to charge a battery. This operation is generally referred to as regenerative braking, in which kinetic energy of the vehicle is converted into electric energy. In this way, the kinetic energy is recovered.
For example, Japanese Laid-Open Patent Application Publication No. Hei. 05-191904 discloses a technique in which a regenerative braking force corresponding to a typical engine braking force is generated based on the degree to which an accelerator is open (accelerator displacement amount) in an electric vehicle including a motor as a driving power source. According to this disclosure, a small degree to which an accelerator pedal is depressed by a driver is set as a reference accelerator displacement amount. When an accelerator displacement amount is not less than the reference accelerator displacement amount, the wheels are driven by the motor, whereas when the accelerator displacement amount is less than the reference accelerator displacement amount, regenerative braking is initiated.
However, in this technique, when the driver is depressing a brake pedal and a service brake is actuated, regenerative braking does not occur. Because of this, if the driver depresses the brake pedal, the kinetic energy of the electric vehicle cannot be recovered. Since the regenerative braking force cannot be utilized, a burden placed on the service brakes tends to increase.